In my software engineering program, we talk a lot about mission critical projects. Software needs to be really engineered and architected when in those cases when there can’t be any mistakes when the code first goes into production—the code for space rockets, the code for military applications. No one dies when Facebook goes down for a minute, but when there’s a divide by zero error in a manned rocket, results can be catastrophic. It reminds me of that FedEx commercial—"When it absolutely, positively", must be done right the first time.